warning about scam email

I have a good friend who recieved an email supposedly from the FBI and sid it had an arrest warrant.I know him well and it is not right for one.It said he needs to open it immediately.This has to be a scam or virusTHe sender tag looked something like this

FBIoffice @AOL
IT had nothing like an official look to it.I told him he is a sorry criminal as all he gets is an email,watch for a email from the SWAT team